The Pathobiology and Reversibility of Prediabetes in a Biracial Cohort (PROP-ABC) study proposes to study an extant cohort, comprising ~400 normoglycemic African American and Caucasian offspring of parents with type 2 diabetes for an additional 5-year. The subjects were enrolled between 2006 and 2009 and have been followed up to 2012, during which 11 have developed diabetes and 100 developed prediabetes, without evidence of racial disparities. The objective of the present proposal is to gain a fuller understanding of the natural history and metabolic predictors of early glucose abnormalities, by assessing the role of race during the second wave of glycemic progression, and the time dependency of reversibility of prediabetes. The study tests 4 hypotheses: 1) Among offspring of parents with type 2 diabetes, early progression from normal to impaired glucose regulation (within 5 yr) occurs in the highest-risk subjects independently of race, whereas late progression (5-10 yr) displays racial disparities, and is predicted by physiological, biochemical and behavioral markers;2) Early microvascular complications, peripheral vascular disease (PVD), and endothelial dysfunction manifest during transition from normal to impaired glucose regulation, display racial disparities, and are predicted by glycemic and nonglycemic factors;3) The "metabolically healthy" insulin-sensitive obese (ISO) phenotype displays racial disparities in its association with cardiometabolic risk factors and incident dysglycemia among African-Americans and Caucasians offspring of parents with type 2 diabetes;and 4) Duration of the prediabetic state is a major determinant of, and is inversely related to, the efficacy of lifestyle intervention to induce regression of the prediabetic phenotype and restoration of normal glucose regulation. The 100 participants with prediabetes will receive Intensive Lifestyle intervention (ILI), to reverse prediabetes and restore normoglycemia. The ~260 participants who have maintained normal glucose status will continue follow-up for 5 years;persons who develop prediabetes will immediately receive ILI. Understanding the predictors of the escape from normoglycemia, the role of race, and the reversibility of new-onset prediabetes is of utmost importance, because the discovery of interventions for reversal of prediabetes will also help eliminate ethnic disparities in downstream diabetes events. The additional 5 years of follow-up will provide data on 10-yr rates and predictors of incident prediabetes, racial patterns during the second wave of progression, and, time-dependent reversibility of prediabetes. Focusing on prediabetes is of immense public health significance, as its successful reversal prevents diabetes and associated complications.

Public Health Relevance

The reasons for the epidemics of diabetes and prediabetes, and why individuals from certain populations suffer at higher rates are not well known. In the Pathobiology and Reversibility of Prediabetes in a Biracial Cohort (PROP-ABC) study, nearly 400 African Americans and Caucasians whose parents have type 2 diabetes will undergo repeated testing to determine what factors lead to the occurrence of prediabetes, and whether race still plays a major role in a setting where everyone being studied has one or both parents with diabetes. The PROP-ABC Study also will test whether proper nutrition, increased physical activity, and maintaining healthy weight soon after the occurrence of prediabetes will return people's metabolism back to normal.